尝试使用 ROLLUP 后对查询进行排序答案

【问题标题】：Trying to order a query after using ROLLUP尝试使用 ROLLUP 后对查询进行排序
【发布时间】：2014-05-30 07:55:35
【问题描述】：

在mysql中，我需要按年/月顺序排列结果：

Month          Mod1    Mod2    Mod3
Jan/2013        5       4       2
Jan/2013        1       5       3
Total           6       9       5
Feb/2013        6       3       2
Feb/2013        2       1       4
Total           8       4       6
Mar/2014        6       3       2
Mar/2014        2       1       4
Total           8       4       6

按年/月顺序排列应该是：

Month          Mod1    Mod2    Mod3
Mar/2014        6       3       2
Mar/2014        2       1       4
Total           8       4       6
Feb/2013        6       3       2
Feb/2013        2       1       4
Total           8       4       6
Jan/2013        5       4       2
Jan/2013        1       5       3
Total           6       9       5

查询是：

SELECT
   month,
   year,
   SUM(IF(mod = 1, 1, 0)) AS mod1,
   SUM(IF(mod = 2, 1, 0)) AS mod2,
   SUM(IF(mod = 3, 1, 0)) AS mod3
FROM
   DW_RM_Log
WHERE
   ...
GROUP BY
   year, month
WITH ROLLUP
HAVING year IS NOT NULL AND month IS NOT NULL

我不能只在末尾插入 ORDER BY 年月 DESC，因为我收到以下错误：'SQLSTATE[HY000]: 一般错误：1221 CUBE/ROLLUP 和 ORDER BY 的使用不正确'。有什么建议吗？

【问题讨论】：

标签： mysql sql

【解决方案1】：

在 MySQL 中，group by 进行排序。尽管 implicit 排序现在已被弃用，但您仍然可以安全地进行显式排序。以下应该做你想做的事：

SELECT month, year,
       SUM(mod = 1) AS mod1, SUM(mod = 2) AS mod2, SUM(mod = 3) AS mod3
FROM DW_RM_Log
WHERE ...
GROUP BY year DESC, month DESC WITH ROLLUP
HAVING year IS NOT NULL AND month IS NOT NULL;

请注意，我还简化了 sum() 条件。在 MySQL 中，您可以只使用条件本身，而不是包括 if()。

【讨论】：

【解决方案2】：

要回答您关于在 WITH ROLLUP 查询上施加 ORDER BY 的具体问题，您只需将其转换为子查询：

SELECT *
FROM
(
SELECT
   month,
   year,
   SUM(IF(mod = 1, 1, 0)) AS mod1,
   SUM(IF(mod = 2, 1, 0)) AS mod2,
   SUM(IF(mod = 3, 1, 0)) AS mod3
FROM
   DW_RM_Log
WHERE
   ...
GROUP BY
   year, month
WITH ROLLUP
HAVING year IS NOT NULL AND month IS NOT NULL
) a 
ORDER BY year, month DESC

【讨论】：